1. Field of Invention
This invention relates to a free floating open ocean farming system which produces and harvests macroalgal plants for production of methane and carbon dioxide gases and, more particularly, to a platform structure used to grow the macroalgal plants.
2. Description of Related Art
There is presently a growing concern that continued unabated emissions of carbon dioxide may lead to a global temperature rise or other climatic change. Over the past 100 years, anthropogenic sources of carbon dioxide from fossil fuel use have added approximately 150 gigatons of carbon to the earth's atmosphere. This quantity represents approximately a 25 percent increase over the pre-anthropogenic level. If current projected increases in energy use continue throughout the twenty-first century, it will be extremely difficult to limit maximum carbon dioxide concentration in the earth's atmosphere to twice the pre-anthropogenic levels; i.e. 600 parts per million. Use of the natural algae carbon cycle to refossilize carbon dioxide has been proposed in the articles, "Algal Refossilization of Atmospheric Carbon Dioxide", EAR-7401, July, 1991 Neushul Mariculture, Inc. September 1990 and "A Summary Description of the Second Workshop on the Role of Macroalgal Oceanic Farming in Global Change," Electric Power Research Institute, Report OCBD 7303, (Jul. 23, 24, 1990). In order to seriously consider large-scale carbon dioxide mitigation of 5 to 10 gigatons of carbon annually, it will be necessary to develop large-scale phytomass production systems. Terrestrial systems are limited to perhaps 2-3 gigatons of carbon uptake per year and may not sequester this carbon for periods of centuries. Therefore, it will be necessary if the global carbon buildup affects the global climate as projected, to develop large-scale oceanic based carbon absorption, sequestering, and displacement systems. One such system is that disclosed in patent application Ser. No. 07/956,944, commonly assigned to the assignee of the present application, and hereby incorporated by reference herein.
Open ocean macroalgal farms require a base structure to hold the plants. A variety of macroalgal farm structures for application on the continental shelves or the open ocean have been proposed and, in a few cases, tested in the past. Many of these structures have been destroyed when deployed in open oceans. A successful structure must be able to dissipate very high quantities of energy in order to withstand the forces associated with "orbiting" motions when the system is allowed to drift in a circular pattern. Therefore, it is apparent that what is needed is a macroalgal farm system having satisfactory structural design to retain the algal mat and withstand the tremendous forces imposed by the sea.